Comcast (finally) brings security extensions to DNS

Comcast - one of the largest ISPs in the US - has deployed new technology designed to protect the internet against a well-known form of attack that allows attackers to surreptitiously lure end users to impostor websites.

For now, Comcast users who want to use the technology, known as DNSSEC, or DNS Security Extensions, must manually configure their preference by changing their DNS server's IP addresses to 75.75.75.75 and 75.75.76.76, Comcast said on Tuesday. By the end of next year, the ISP plans to make DNSSEC available to all of its customers.

The move came as OpenDNS, which operates publicly available domain name system servers for free, criticized DNSSEC and said it was jump starting a competing measure known as DNSCurve. OpenDNS engineer Matthew Dempsky said it uses much stronger cryptography than DNSSEC and is also much easier to deploy and maintain.

"Aside from its lack of adoption, DNSSEC isn't even a very satisfactory solution," Dempsky wrote. "It adds tremendous complexity to an already fragile protocol, significantly increases DNS traffic in size, encourages questionable security practices, and hamstrings many modern uses of DNS."

A recent survey found that only 20 percent of US government agencies had deployed DNSSEC, despite a December 31 deadline to adopt the standard. The technical imperfections of DNSSEC aside, its uneven adoption is also a major limitation because it is effective only if it is used uniformly across the internet.

DNSSEC uses public key cryptography to digitally validate that IP results returned during a DNS query point to the authentic corresponding domain name. It's designed to counter DNS cache poisoning attacks such as those developed in 2008 by researcher Dan Kaminsky.

The hierarchical system, which was first proposed 15 years ago, requires authentication at every step in the DNS process. At the moment, only two of the 13 root servers are digitally signed and many the net's top level domains still haven't deployed it. The US government in June pledged to sign the root zone it maintains, but so far netizens at large must still rely on the unsecured root for domain lookups. ®